Stockholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning	$ 277,537	$ 302,740	$ 326,204	$ 365,093	$ 398,101	$ 419,476	$ 326,204	$ 419,476
Balance, beginning (in shares)			47,200,695				47,200,695
Shares issued under stock option and employee stock purchase plans	257	133	$ 694	2,306	71	304
Stock-based compensation	7,121	5,217	4,340	4,496	3,454	3,153
Unrealized gain (loss) on marketable securities	63	(51)	863	305	(529)	(1,782)	$ 875	(2,006)
Net loss	(38,260)	(30,502)	(29,361)	(26,784)	(36,004)	(23,050)	(98,123)	(85,838)
Balance, ending	$ 246,718	277,537	302,740	345,416	365,093	398,101	$ 246,718	345,416
Balance, ending (in shares)	47,264,197						47,264,197
Aggregate gross offering price available	$ 50,000						$ 50,000
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning	$ 47	$ 47	$ 47	$ 47	$ 47	$ 47	$ 47	$ 47
Balance, beginning (in shares)	47,253,813	47,244,681	47,200,695	46,764,703	46,754,348	46,730,198	47,200,695	46,730,198
Shares issued under stock option and employee stock purchase plans (in shares)	10,384	9,132	43,986	331,360	10,355	24,150
Balance, ending	$ 47	$ 47	$ 47	$ 47	$ 47	$ 47	$ 47	$ 47
Balance, ending (in shares)	47,264,197	47,253,813	47,244,681	47,096,063	46,764,703	46,754,348	47,264,197	47,096,063
Additional Paid-In Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning	$ 1,591,213	$ 1,585,863	$ 1,580,829	$ 1,568,124	$ 1,564,599	$ 1,561,142	$ 1,580,829	$ 1,561,142
Shares issued under stock option and employee stock purchase plans	257	133	694	2,306	71	304
Stock-based compensation	7,121	5,217	4,340	4,496	3,454	3,153
Balance, ending	1,598,591	1,591,213	1,585,863	1,574,926	1,568,124	1,564,599	1,598,591	1,574,926
Accumulated Other Comprehensive Income
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning	2,072	2,123	1,260	(417)	112	1,894	1,260	1,894
Unrealized gain (loss) on marketable securities	63	(51)	863	305	(529)	(1,782)
Balance, ending	2,135	2,072	2,123	(112)	(417)	112	2,135	(112)
Accumulated Deficit
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning	(1,315,795)	(1,285,293)	(1,255,932)	(1,202,661)	(1,166,657)	(1,143,607)	(1,255,932)	(1,143,607)
Net loss	(38,260)	(30,502)	(29,361)	(26,784)	(36,004)	(23,050)
Balance, ending	$ (1,354,055)	$ (1,315,795)	$ (1,285,293)	$ (1,229,445)	$ (1,202,661)	$ (1,166,657)	$ (1,354,055)	$ (1,229,445)